BIOLOGY AND CONTROL OF CHIGGERS. 15 



It would appear from this that the dusting with sulphur inside 

 the hosiery and underwear is sufficient if it is so applied as to be 

 well distributed. Later tests fully demonstrated that a single appli- 

 cation was sufficient if well distributed. 



The " pinch method," i. e., applying a powder insecticide by pick- 

 ing up small amounts with the thumb and fore finger, while well 

 adapted for dusting lousy chickens, for example, was observed to 

 be both tedious and wasteful, hence other methods were resorted to. 



Application by means of a talcum shaker was made on August 

 9, 1919, followed by exposure at Vienna, Va. Examination that 

 night showed it to be 100 per cent effective. 



On August 15, 1920, application was made with a pepper shaker. 

 A considerable tendency of the sulphur to clog the small holes of 

 the top was noticed, but by violent agitation a fairly even appli- 

 cation was made. Only the inside of the stockings and the lower 

 part of the underwear were treated. Exposure for about 3 hours 

 was made in the woods north of Chesapeake Beach, Md. Later 

 examination showed 100 per cent efficiency. It should be added 

 that if sulphur is dusted by means of a salt or pepper shaker, after 

 the operation all unused sulphur should be removed and the con- 

 tainer washed. This will prevent the tarnishing of the metal parts 

 of the shaker. 



Mr. Flint, of the State Natural History Survey of Illinois, states 

 that he has applied sulphur by means of a small bag and also by 

 the "pinch method," with good results. Dr. J. W. Folsom also 

 reports good results from sulphur treatment by the " pinch method." 

 During the summers of both 1919 and 1920 several members of 

 the bureau staff tried the use of sulphur, and in every case good 

 results were reported and usually complete protection. 



DESTRUCTION OF BREEDING PLACES. 



It is hoped that the observations made on the habits and local 

 distribution will enable much more to be done to advantage in de- 

 stroying the breeding places of chiggers. Especially is this method 

 of attack to be recommended about private dwellings and in poorly 

 kept public parks and at summer resorts. Already its feasibility 

 has been demonstrated. In and around Washington many chigger- 

 infested lots or fields have been automatically rendered free of 

 chiggers by turning these to cultivation or cleaning away the rough 

 growth. Prof. F. L. Washburn {!%) has the following to say in 

 regard to the effect of cutting down bushy growth in Minnesota : 



Capt. Zimmerman, living on Enchantment Island, Lake Minnetonka, having 

 found this pest troublesome on his own island and upon the neighboring Phelps 

 Island, has reduced their numbers materially by cutting out much underbrush, 

 thus letting in the sunlight. 



